EP1736490A2 - Polymer blend based on polycarbonate polyols - Google Patents

Abstract

An aqueous coating material comprises (A) hydroxyl-free polyurethane and/or polyurethane-urea, (B) ionically modified, hydroxyl- and/or amino-containing polyurethane and/or polyurethane-urea, and (C) crosslinker(s). Polyurethane and/or polyurethane-urea components (A) and (B) comprise polycarbonate polyol containing >=25 wt.% 1,4-butanediol as synthesis component. Independent claims are included for: (1) a two-component paint comprising the above coating materials; (2) a coating on the surface of mineral building materials, metallic surfaces, or asphaltic or bituminous coverings, paints and sealants for wood and wood-based materials or plastics surfaces, or high-gloss varnishes, comprising the above coating material; (3) a soft feel paint on plastic substrates or wood substrates, comprising the above coating material; and (4) a multi-coat system comprising a topmost coat (e.g. clearcoat or topcoat film), and a soft feel paint.

Description

The invention relates to aqueous coating compositions based on polycarbonate polyols, a process for their preparation and use as a soft-feel coating.

Polyurethane-polyurea dispersions (PU dispersions) and aqueous formulations of PU dispersions are known in the art. An important field of application of aqueous preparations of ionically modified PU dispersions lies in the area of the coating of plastic parts.

Due to aesthetic and technical requirements, plastic parts are usually painted to protect the plastic from external influences, such as sunlight, chemical, thermal and mechanical stress, to achieve certain hues and color effects, to cover defects of the plastic surface or to the plastic surface a pleasant grip To give (haptic). To improve the haptic properties of plastic parts so-called softfeel paints are increasingly used in recent years. "Softfeel effect" in the sense of the present invention denotes a special feel (feel) of the painted surface; This feel can be described in terms of velvety, soft, rubbery, warm. Following the trend of avoiding emissions of solvents into the environment, aqueous softfeel lacquers based on polyurethane chemistry have become established in recent years, as exemplified in US Pat DE-A 44 06 159 be revealed. In addition to an excellent softfeel effect, these coatings also give coatings with good resistance and protective effect for the plastic substrate. In the meantime, however, it has been shown that these lacquers and coatings often have inadequate resistance to hydrolysis.

The object of the present invention was therefore to provide coating compositions which, in addition to the o.g. mechanical and haptic properties, compared to prior art coating compositions, lead to significantly more hydrolysis-stable coatings.

Such as in the DE-A 44 06 159 described plastic coating compositions with the desired haptic Softfeel properties consist of a part of polyurethane dispersions that have no appreciable amounts of hydroxy-functional groups.

DE-A 101 22 444 describes hydrolystable, ionically and / or nonionically hydrophilicized polyurethane-polyurea- (PUR) -dispersions based on polycarbonate polyols and polytetramethylene glycol polyols. The dispersions lead to a variety of substrates in one-component Coating agents for hydrolysis-stable, kink- and scratch-resistant coatings. However, an application of these dispersions as softfeel paints is not described.

It has now been found that aqueous two-component (2K) coating compositions containing both non-functional PUR polymers based on specific polycarbonate polyols and hydrophilic, hydroxyl-containing PUR polymers based on specific polycarbonate polyols exhibit excellent hydrolytic stability and at the same time the desired haptic properties.

• I) hydroxylgruppenfreie Polyurethane und/oder Polyurethanharnstoffe,
• II) ionisch modifizierte, hydroxylgruppenhaltige Polyurethane und/oder Polyurethanharnstoffe sowie
• III) mindestens einen Vernetzer,

dadurch gekennzeichnet, dass die Komponenten (I) und (II) Polycarbonatpolyole enthalten, die einen Anteil von mindestens 25 Gew.-% an 1,4-Butandiol als Aufbaukomponente aufweisen.The present invention therefore relates to aqueous coating compositions containing

• I) hydroxyl-free polyurethanes and / or polyurethane ureas,
• II) ionically modified, hydroxyl-containing polyurethanes and / or polyurethane ureas and
• III) at least one crosslinker,

characterized in that the components (I) and (II) contain polycarbonate polyols which have a proportion of at least 25 wt .-% of 1,4-butanediol as a synthesis component.

• A.1) Polyisocyanate,
• A.2) polymere Polyole mit einem zahlenmittleren Molekulargewicht von Mn 200 bis 8000 g/mol, die Polycarbonatpolyole enthalten, die mindestens zu 25 Gew.-% aus 1,4-Butandiol als Aufbaukomponente bestehen,
• A.3) niedermolekulare Verbindungen des Molgewichts Mn 62 bis 400 g/mol die in Summe über zwei oder mehr Hydroxyl- und/oder Aminogruppen verfügen,
• A.4) Verbindungen, die über eine Hydroxy- oder Aminogruppe verfügen,
• A.5) isocyanatreaktive, ionische oder potentiell ionische Verbindungen sowie
• A.6) isocyanatreaktive, nichtionische hydrophile Verbindungen eingesetzt.

In the process for preparing the non-functional polyurethane polymers (I) are used as synthesis components selected from the group of components

• A.1) polyisocyanates,
• A.2) polymeric polyols having a number average molecular weight of Mn 200 to 8000 g / mol, which contain polycarbonate polyols which consist of at least 25 wt .-% of 1,4-butanediol as a synthesis component,
• A.3) low molecular weight compounds of molecular weight Mn 62 to 400 g / mol which in total have two or more hydroxyl and / or amino groups,
• A.4) compounds which have a hydroxy or amino group,
• A.5) isocyanate-reactive, ionic or potentially ionic compounds as well
• A.6) isocyanate-reactive, nonionic hydrophilic compounds used.

Suitable polyisocyanates of component A.1) are the aromatic, araliphatic, aliphatic or cycloaliphatic polyisocyanates of an NCO functionality known per se to the person skilled in the art of preferably ≥ 2, which may also have iminooxadiazinedione, isocyanurate, uretdione, urethane, allophanate, biuret, urea, oxadiazinetrione, oxazolidinone, acylurea and / or carbodiimide structures. These can be used individually or in any mixtures with each other.

Examples of suitable polyisocyanates are hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), the isomeric dicyclohexylmethane-4,4'-diisocyanate or mixtures thereof of any isomer content and 1,4-cyclohexyl diisocyanate.

As an example of a non-modified polyisocyanate having more than 2 NCO groups per molecule, see e.g. 4-Isocyanatomethyl-1,8-octane diisocyanate (nonane triisocyanate) called.

Preference is given to polyisocyanates or polyisocyanate mixtures of the abovementioned type with exclusively aliphatically and / or cycloaliphatically bonded isocyanate groups.

Particularly preferred are hexamethylene diisocyanate, isophorone diisocyanate, the isomeric dicyclohexylmethane-4,4'-diisocyanate and mixtures thereof.

Hydroxyl-containing polycarbonate polyols according to the definition of component A.2) are obtainable by reaction of carbonic acid derivatives, for example diphenyl carbonate, dimethyl carbonate or phosgene with diols. The hydroxy-functional polycarbonate polyols A.2) to be used according to the invention have an average hydroxyl functionality of 1.6 to 4, preferably 1.8 to 3 and particularly preferably 1.9 to 2.3 and a number-average molecular weight of 240 to 8000 g / mol from 500 to 3000 g / mol, more preferably from 750 to 2500 g / mol. The preparation of the polycarbonate polyols is preferably carried out according to the in the EP-A 1 404 740 (Pp. 6-8, examples 1-6) and EP-A 1 477 508 (Page 5, Example 3) described manufacturing method.

As diols come e.g. 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,12-dodecanediol, neopentyl glycol, 1,4-bis-hydroxymethylcyclohexane, 2-methyl-1,3-propanediol and trimethylpentanediol-1 , 3 in question, wherein the proportion of 1,4-butanediol is at least 25 wt .-% of the diol components used. The diol component preferably contains 45 to 100% by weight 1,4-butanediol, and 0 to 55% by weight 1,6-hexanediol, particularly preferably 60 to 100% by weight 1,4-butanediol and 0 to 40% by weight .-% 1,6-hexanediol.

The hydroxylpolycarbonates are preferably linear, but may optionally be branched by the incorporation of polyfunctional components, in particular low molecular weight polyols. Particularly preferred components A.2) are based on mixtures of 1,4-butanediol and 1,6-hexanediol and have an average hydroxyl functionality of 1.9 to 2.05.

Polyester polyols which have a molecular weight Mn of from 400 to 6000 Da, more preferably from 600 to 3000 Da, can likewise be used as polymeric polyols A.2). Their hydroxyl number is generally 22 to 400 mg KOH / g, preferably 50 to 200 mg KOH / g and more preferably 80 to 160 mg KOH / g, and have an OH functionality of 1.5 to 6, preferably 1.8 to 4, and more preferably from 1.9 to 3.3.

Highly suitable examples are the on are the known polycondensates of di- and optionally polyols and di- and optionally polycarboxylic acids or hydroxycarboxylic acids or lactones. Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols for the preparation of the polyesters. Examples of suitable diols are ethylene glycol, butanediol (1,4), hexanediol (1,6), neopentyl glycol. Examples of suitable polyols which may be used here are trimethylolpropane, glycerol or pentaerythritol.

Suitable dicarboxylic acids are preferably phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, or adipic acid. Anhydrides of these acids are also suitable, as far as they exist. As a result, for the purposes of the present invention, the anhydrides are encompassed by the term "acid". Monocarboxylic acids such as benzoic acid and hexanecarboxylic acid can also be used, provided that the average functionality of the polyol is higher than 2. As polycarboxylic acid which may optionally be used in smaller amounts, trimellitic acid may be mentioned here.

Further suitable components A.2) are the polylactone and polyether polyols known from polyurethane chemistry, insofar as they correspond to the abovementioned criteria in terms of functionality and molecular weight.

The proportion of the hydroxyl polycarbonates in the sum of the polyols used from A.2) for the preparation of the polymers (I) or (II) is 35 to 100 wt .-%, preferably 45 to 100 wt .-% and particularly preferably 65 to 100 wt .-%.

The low molecular weight polyols A.3) used to build up the polyurethane resins generally cause stiffening and / or branching of the polymer chain. The molecular weight is preferably between 62 and 200 Da. Suitable polyols may contain aliphatic, alicyclic or aromatic groups. Mentioned here are, for example, the low molecular weight polyols having up to about 20 carbon atoms per molecule, such as. As ethylene glycol, diethylene glycol, 1,4-butanediol, 1,3-butylene glycol, cyclohexanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol and trimethylolpropane, glycerol or pentaerythritol.

Di- or polyamines as well as hydrazides can also be used as A.3), e.g. Ethylenediamine, 1,2- and 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, isophoronediamine, isomer mixture of 2,2,4- and 2,4,4-trimethylhexamethylenediamine, 2-methylpentamethylenediamine, diethylenetriamine, 1,3- and 1,4-xylylenediamine, α, α, α ', α'-tetramethyl-1,3- and 1,4-diaminodicyclohexylmethane, dimethylethylenediamine, hydrazine or adipic dihydrazide. In principle, compounds which contain active hydrogen with respect to NCO groups of different reactivity, such as compounds which, in addition to a primary amino group, also have secondary amino groups or OH groups in addition to an amino group (primary or secondary), are also suitable as A.3).

The polyurethane resins I) and II) may also contain, if appropriate, building blocks A.4), which are located in each case at the chain ends and terminate them. These building blocks are derived, on the one hand, from monofunctional compounds reactive with NCO groups, such as monoamines, in particular mono-secondary amines or monoalcohols.

By ionic or potentially ionic hydrophilizing compounds A.5) are meant all compounds which have at least one isocyanate-reactive group and at least one functionality such as -COOY, -SO ₃ Y, -PO (OY) ₂ (Y, for example = H, NH ₄ ⁺ , metal cation), -NR ₂ , -NR ₃ ⁺ (R = H, alkyl, aryl), which undergo a pH-dependent dissociation equilibrium when interacting with aqueous media and in this way charge negative, positive or neutral can be. Preferred isocyanate-reactive groups are hydroxyl or amino groups.

Suitable ionically or potentially ionically hydrophilizing compounds according to the definition of component A.5) are, for example, mono- and dihydroxycarboxylic acids, mono- and diaminocarboxylic acids, mono- and dihydroxysulfonic acids, mono- and diaminosulfonic acids and also mono- and dihydroxyphosphonic acids or mono- and diaminophosphonic acids and their salts such as dimethylolpropionic acid, dimethylolbutyric acid, hydroxypivalic acid, N- (2-aminoethyl) -β-alanine, 2- (2-aminoethylamino) -ethanesulfonic acid, ethylenediamine-propyl- or -butylsulfonic acid, 1,2- or 1,3-propylenediamine β-ethylsulfonic acid, malic acid, citric acid, glycolic acid, lactic acid, glycine, alanine, taurine, lysine, 3,5-diaminobenzoic acid, an addition product of aliphatic diamines such as ethylenediamine (EDA) or isophoronediamine IPDA and acrylic acid ( EP-A 0 916 647 Example 1) and its alkali and / or ammonium salts; Polyethersulfonat, the propoxylated adduct of 2-butenediol and NaHSO ₃ , for example described in the DE-A 2 446 440 (Page 5-9, Formula I-III) and compounds which can be converted into cationic groups, for example amine-based, blocks such as N-methyl-diethanolamine as hydrophilic structural components contain. Furthermore, cyclohexylaminopropanesulfonic acid (CAPS) as in the WO-A 01/88006 used as a compound according to the definition of component A.5).

For the construction of component I), preference is given to those compounds A.5) which have carboxy or carboxylate and / or sulfonate groups and / or ammonium groups. Particularly preferred ionic compounds A.5) are those which contain carboxyl and / or sulfonate groups as ionic or potentially ionic groups, such as the salts of N- (2-aminoethyl) -β-alanine, the 2- (2-amino) ethylamino) ethanesulfonic acid or the addition product of IPDI and acrylic acid ( EP-A 0 916 647 Example 1) and the dimethylolpropionic acid.

Suitable nonionic hydrophilic compounds according to the definition of component A.6) are e.g. Polyoxyalkylene ethers containing at least one hydroxy or amino group. These polyethers contain from 30% to 100% by weight of building blocks derived from ethylene oxide.

The polyalkylene oxide polyether alcohols are either pure polyethylene oxide polyethers or mixed polyalkylene oxide polyethers whose alkylene oxide units consist of at least 30 mol%, preferably at least 40 mol%, of ethylene oxide units. Preferred nonionic compounds are monofunctional mixed polyalkylene oxide polyethers which have at least 40 mol% of ethylene oxide and not more than 60 mol% of propylene oxide units.

For the PUR polymers (I) it is preferred to use a combination of ionic and nonionic hydrophilicizing agents according to the definitions of components A.5) and A.6). Particularly preferred are combinations of nonionic and anionic hydrophilicizing agents.

Preference is given to 5 to 45 wt .-% of component A.1), 50 to 90 wt .-% of component A.2), 1 to 30 wt .-% of the sum of compounds A.3) and A.4), 0 from 0 to 15% by weight of component A6), the sum of A.5) and A.6) being from 0.1 to 27% by weight, and the sum of all components added to 100 wt .-%.

10 to 40% by weight of component A.1), 55 to 85% by weight of component A.2), 1 to 25% by weight of the sum of compounds A.3) and A.4) are particularly preferred, 0 to 10% by weight of component A.5), 0 to 10% by weight of component A.6), the sum of A.5) and A.6) being 0.1 to 20% by weight and the sum of all components added to 100 wt .-%.

Very particular preference is given to 15 to 40% by weight of component A.1), 60 to 85% by weight of component A.2), 1 to 20% by weight of the sum of compounds A.3), 0 to 8% by weight .-% Component A.5), 0 to 10 wt .-% component A.6) used, wherein the sum of A.5) and A.6) is 0.1 to 18 wt .-% and the sum of all components to 100 wt .-% added.

The coating compositions according to the invention comprise PU polymers (I) which are used in the form of their aqueous PU dispersion (I).

The process for the preparation of the aqueous PU dispersion (I) can be carried out in one or more stages in homogeneous or in multistage reaction, partly in disperse phase. After completely or partially carried out polyaddition from A.1) - A.6) takes place a dispersing, emulsifying or dissolving step. This is followed, if appropriate, by a further polyaddition or modification in disperse phase.

For the preparation of the aqueous polyurethane dispersions (I), all known from the prior art methods such as. Example, prepolymer mixing method, acetone method or Schmelzdipergierverfahren can be used. The PU dispersion (I) is preferably prepared by the acetone process.

For the preparation of the PU dispersion (I) by the acetone process are usually the components A.2) to A.6), which may have no primary or secondary amino groups and the polyisocyanate component A.1) for the preparation of an isocyanate-functional polyurethane Prepolymer presented in whole or in part and optionally diluted with a water-miscible but isocyanate-inert solvent and heated to temperatures ranging from 50 to 120 ° C. To accelerate the isocyanate addition reaction, the catalysts known in polyurethane chemistry can be used. Preference is given to dibutyltin dilaurate.

Suitable solvents are the usual aliphatic, ketofunctional solvents, e.g. Acetone, butanone, which can be added not only at the beginning of the preparation, but possibly also in parts later. Preferred are acetone and butanone.

Subsequently, the components of A.1) - A.6) which may not have been added at the beginning of the reaction are subsequently metered in.

In the preparation of the polyurethane prepolymer, the molar ratio of isocyanate groups to isocyanate-reactive groups is 1.0 to 3.5, preferably 1.1 to 3.0, particularly preferably 1.1 to 2.5.

The reaction of the components A.1) - A.6) to the prepolymer takes place partially or completely, but preferably completely. Thus, polyurethane prepolymers containing free isocyanate groups are obtained in bulk or in solution.

After or during the preparation of the polyurethane prepolymers, if this has not yet been carried out in the starting molecules, the partial or complete salt formation of the anionically and / or cationically dispersing groups takes place. In the case of anionic groups, bases such as tertiary amines, e.g. Trialkylamines having 1 to 12, preferably 1 to 6 carbon atoms used in each alkyl radical. Examples of these are trimethylamine, triethylamine, methyldiethylamine, tripropylamine and diisopropylethylamine. The alkyl radicals may, for example, also carry hydroxyl groups, as in the case of the dialkylmonoalkanol, alkyldialkanol and trialkanolamines. If appropriate, inorganic bases such as ammonia or sodium or potassium hydroxide may also be used as neutralizing agents. Preference is given to triethylamine, triethanolamine, dimethylethanolamine or diisopropylethylamine.

The molar amount of the bases is between 50 and 100%, preferably between 70 and 100% of the molar amount of the anionic groups. In the case of cationic groups, sulfuric acid dimethyl ester or succinic acid are used. If only nonionically hydrophilized compounds A.6) with ether groups are used, the neutralization step is omitted. The neutralization can also take place simultaneously with the dispersion in which the dispersing water already contains the neutralizing agent.

Subsequently, in a further process step, if not yet done or only partially done, the resulting prepolymer with the aid of aliphatic ketones such as acetone or butanone.

Subsequently, possible NH ₂ - and / or NH-functional components are reacted with the remaining isocyanate groups. This chain extension / termination can be carried out either in a solvent before dispersing, during dispersion or in water after dispersion. The chain extension is preferably carried out in water before dispersion.

If compounds corresponding to the definition of A.5) with NH ₂ or NH groups are used for chain extension, the chain extension of the prepolymers preferably takes place before the dispersion.

The chain extension, ie the equivalent ratio of NCO-reactive groups of the compounds used for chain extension to free NCO groups of the prepolymer is between 40 to 150%, preferably between 70 to 120%, particularly preferably between 80 to 120%.

The aminic components [A.3), A.4), A.5)] can optionally be used individually or in mixtures in water- or solvent-diluted form in the process according to the invention, wherein basically any order of addition is possible.

If water or organic solvents are used as diluents, the diluent content is preferably 70 to 95% by weight.

The preparation of the PU dispersion (I) from the prepolymers takes place after the chain extension. To this end, the dissolved and chain extended polyurethane polymer is optionally sheared under high shear, e.g. vigorous stirring, either added to the dispersing water or, conversely, the dispersing water is stirred into the prepolymer solutions. Preferably, the water is added to the dissolved prepolymer.

The solvent still present in the dispersions after the dispersion step is then usually removed by distillation. A removal already during the dispersion is also possible.

Depending on the degree of neutralization and content of ionic groups, the dispersion can be adjusted very finely divided, so that it has practically the appearance of a solution, but also very coarse-particle settings are possible, which are also sufficiently stable.

The solids content of the PU dispersion (I) is between 25 to 65%, preferably 30 to 60% and particularly preferably between 40 to 60%.

The ionically modified, hydroxyl-containing polyurethanes and / or polyurethane ureas (II) contain 5 to 45 wt .-% of component A.1), 50 to 94.5 wt .-% of components A.2), 0 to 15 wt .-% component A.3), 0.5 to 12 wt .-% component A.5), 0 to 15 wt .-% component A.6) wherein the sum of all components added to 100 wt .-%.

The ionically modified hydroxyl-containing polyurethanes and / or polyurethane ureas (II) preferably contain 7.5 to 35% by weight of component A.1), 60 to 90% by weight of components A.2a), 0 to 10% by weight. Components A.3), 2.5 to 7.5 wt .-% component A.5), 0 to 12.5 wt .-% component A.6) wherein the sum of all components added to 100 wt .-%.

Most preferably, the ionically modified hydroxyl-containing polyurethanes and / or polyurethane ureas (II) contain from 10 to 25% by weight of component II.1), 65 to 85 % By weight of components A.2), 1.5 to 5% by weight of component A.3), 3 to 7% by weight of component A.5), 0 to 10% by weight of component A.6) wherein the sum of all components added to 100 wt .-%.

As component A.3), only those compounds are suitable which are OH-functional. Components A.4) are not used to build up the polymers (II).

The ionically modified, hydroxyl-containing polyurethanes and / or polyurethane ureas (II) preferably have a pure ionic hydrophilization according to the definition of components A.5). The coating compositions according to the invention contain the ionically modified, hydroxyl-containing polyurethanes and / or polyurethaneureas (II), which are either converted into the aqueous form during production and thus present as a dispersion or alternatively also in a, optionally water-miscible and isocyanate-inert solvent Solution available.

The ionically modified, hydroxyl-containing polyurethanes and / or polyurethane ureas (II) can be prepared by the usual methods known in the art. The polyurethanes and / or polyurethane ureas (II) differ from the PUR polymers (I) in particular by the nature of the preparation and the type of hydrophilization. They contain carboxylic acid and / or sulfonic acid groups, preferably carboxylic acid groups, which may be at least partially neutralized, as hydrophilic groups. For the preparation of the PUR polymers (II) are therefore preferred as component A.5) those which have carboxy and / or carboxylate groups. Particularly preferred ionic compounds A.5) are dihydroxycarboxylic acids, very particularly preferred are α, α-dimethylolalkanoic acids, e.g. 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid or dihydroxysuccinic acid.

For the preparation of the ionically modified, hydroxyl-containing polyurethanes and / or polyurethane ureas (II) are usually the components A.2), A.3), A.5) and optionally A.6), optionally together with a suitable catalyst and if necessary in presented a suitable solvent. In this mixture, at a temperature of 0 to 140 ° C, preferably 70 to 135 ° C and more preferably at 90 to 130 ° C, a polyisocyanate A.1) is added and allowed to react until the reaction product is isocyanate. The amounts used of components A.1) to A.6) are so dimensioned that per val hydroxyl groups 0.45 to 0.95, preferably 0.55 to 0.90, particularly preferably 0.65 to 0.85 Val isocyanate groups come.

Preferably, the preparation of the ionically modified, hydroxyl-containing polyurethanes and / or polyurethane ureas (II) without addition of organic solvents.

The acid groups incorporated in the prepolymer are at least partially neutralized. This can be done during or after the prepolymer but also during or after the dispersion in water by adding suitable neutralizing agent (see also in PU dispersion (I)). Examples of suitable neutralizing agents are triethylamine, triethanolamine, dimethylethanolamine, ethyldiisopropylamine or diisopropylethylamine. The neutralizing agent is usually used in molar ratio to the acid groups of the prepolymer of 0.3: 1 to 1.3: 1, preferably from 0.6: 1 to 1.1: 1.

Subsequently, the hydroxyl-functional polyurethane is converted by the addition of water or by adding in water in an aqueous dispersion.

The resins of the polyurethane polymers (II) obtainable by the procedure described above have a number-average molecular weight M _{n of} from 1,000 to 30,000 Da, preferably from 1,500 to 10,000 Da, an acid number of from 10 to 80, preferably from 15 to 40 mg KOH / g and a hydroxyl group content of 0.5 to 6 wt .-%, preferably from 1.0 to 4 wt .-%.

The PU dispersions (I) and (II) may additionally contain all additives known for PU dispersions, such as, for example, antioxidants, light stabilizers and / or other auxiliaries and additives as well as fillers.

Crosslinkers (III) are also present in the coating compositions according to the invention. Depending on the choice of crosslinker, both one-component and two-component coatings can be prepared. In the context of the present invention, one-component paints are to be understood as coating agents in which binder component and crosslinker component can be stored together, without a crosslinking reaction taking place in appreciable or detrimental extent for the subsequent application. Two-component coatings in the context of the present invention are understood to mean coating compositions in which binder component and crosslinker component must be stored in separate vessels because of their high reactivity. The two components are mixed just before application and then generally react without additional activation. Suitable crosslinkers III) include, for example, blocked or unblocked polyisocyanate crosslinkers, amide and amine-formaldehyde resins, phenolic resins, aldehyde and ketone resins, e.g. Phenol-formaldehyde resins, resoles, furan resins, urea resins, carbamic acid ester resins, triazine resins, melamine resins, benzoguanamine resins, cyanamide resins or aniline resins. Preference is given to polyisocyanates.

Polyisocyanates with free isocyanate groups are particularly preferably used as crosslinker component (III), since the resulting aqueous polyurethane coatings show a particularly high paint-technical level. Suitable crosslinkers (III) are, for example, paint polyisocyanates such as uretdione, biuret, isocyanurate or iminooxadiazinedione polyisocyanates of hexamethylene diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane or bis (4-isocyanatocyclohexane) methane.

Likewise provided by the present invention is a two-component coating comprising the coating compositions according to the invention.

The PUR polymers (I) and (II) described here are generally sufficiently hydrophilic so that the dispersibility of hydrophobic crosslinkers of component (III) is ensured. If desired, however, it is also possible to add additional external emulsifiers as are known to the person skilled in the art.

However, it is also possible to use water-soluble or dispersible polyisocyanates, as described, for example, in US Pat. obtainable by modification with carboxylate, sulfonate and / or polyethylene oxide groups and / or polyethylene oxide / polypropylene oxide groups are used in component (III).

In principle, of course, it is also possible to use mixtures of different crosslinker resins of the abovementioned type in component (III).

Likewise provided by the present invention is a process for preparing the aqueous coating compositions according to the invention, characterized in that the PU polymers (I) and the PU polymers (II) are dispersed in water and mixed with the crosslinker (III).

The ratio of the crosslinker (III) to the compounds of the components (II) which are reactive with it should be selected such that a ratio of crosslinker-reactive groups from (II) (eg OH groups) to the reactive groups of the crosslinker (at Isocyanate NCO groups) of 0.5: 1.0 to 3.5: 1.0, preferably 1.0: 1.0 to 3.0: 1.0, and more preferably 1.0: 1.0 to 2.5: 1.0 results.

The mixture of components (I) and (II) contains preferably from 5 to 95% by weight (with respect to solid resin), more preferably from 25 to 75% by weight (with respect to solid resin) of component (II), the amount of (I) is to be chosen so that the total amounts of (I) and (II) add up to 100 wt .-% (in terms of solid resin).

As customary auxiliaries and additives, the substances known to the person skilled in the art, such as defoaming agents, thickeners, pigments, dispersants, matting agents, catalysts, anti-skinning agents, anti-settling agents and / or emulsifiers, as well as additives which enhance the desired soft-feel effect, may be present in the coating compositions of the invention be. It is irrelevant at what point in the production of these added to the coating compositions of the invention or incorporated into this.

The aqueous coating compositions according to the invention are suitable for all fields of use in which aqueous coating and coating systems with high surface finish requirements of the films are used, e.g. Coating of mineral building material surfaces, painting and sealing of wood and wood-based materials, coating of metallic surfaces (metal coating), coating and coating of asphalt or bitumen-containing coatings, varnishing and sealing of various plastic surfaces (plastic coating) as well as high-gloss coatings.

However, a preferred use of the coating compositions according to the invention is the production of soft feel effect paints, which ensure good hydrolysis resistances with very good haptic properties. Such coating compositions are preferably used in the plastic coating or in the wood finish, wherein the curing usually takes place at temperatures between room temperature and 130 ° C. The two-component technology with non-blocked polyisocyanates as crosslinker allows the use of comparatively low curing temperatures in o.g. Interval.

Thus softfeel paints containing the coating compositions according to the invention are likewise provided by the present invention.

The aqueous coating compositions of the invention are usually used in single-coat paints or in the clearcoat or topcoat (top coat) of multi-layered structures.

The preparation of the coating can be carried out by the different injection methods such as air pressure, airless or electrostatic spray method using single or optionally two-component spray systems. However, the lacquers and coating compositions containing the binder dispersions according to the invention can also be applied by other methods, for example by brushing, rolling or knife coating.

The present invention likewise relates to a multilayer structure, characterized in that the topmost layer, which is a clear or topcoat layer, contains a softfeel lacquer containing the coating compositions according to the invention.

Examples:

Unless otherwise indicated, all percentages are by weight.

Substances used and abbreviations:

diaminosulphonate:

NH ₂ -CH ₂ CH ₂ -NH-CH ₂ CH ₂ -SO ₃ Na (45% in water)

Desmophen ^® 3600:

Difunctional polyether based on propylene oxide, number average molecular weight 2000 g / mol, OH number 56 mg KOH / g (Bayer AG, Leverkusen, DE)

Polyether LB 25:

(monofunctional polyether based on ethylene oxide / propylene oxide number average molecular weight 2250 g / mol, OH number 25 mg KOH / g (Bayer AG, Leverkusen, DE)

BYK ^® 348:

Wetting agent (BYK-Chemie, Wesel, DE)

Tego- ^Wet® KL 245:

Leveling additive, 50% in water (Tegochemie, Essen, DE)

Aquacer ^® 535:

Wax emulsion (BYK-Chemie, Wesel, DE)

Defoamer DNE:

Defoamer (K. Obermayer, Bad Berleburg, DE)

Sillitin ^® Z 86:

Filler (Hoffmann & Söhne, Neuburg, DE)

Talc ^® IT extra:

Matting agent (Norwegian Talc, Frankfurt, DE)

Bayferrox ^® 318 M:

Color pigment (black) (Bayer AG, Leverkusen, DE)

OK 412:

Matting agents (Degussa, Frankfurt, DE)

Bayhydur® ^® 3100:

Hydrophilic, aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI) with an isocyanate content of 17.4% (Bayer AG, Leverkusen, DE)

MPA:

1-methoxy-2-propyl

The solids contents were determined according to DIN-EN ISO 3251.

NCO contents were determined volumetrically in accordance with DIN-EN ISO 11909, unless expressly stated otherwise.

Example 1 Polyesterpolyol

In a 151-reaction vessel with stirrer, heater and water with a condenser, 1281 g of phthalic anhydride, 5058 g of adipic acid, 6387 g of 1,6-hexanediol and 675 g of neopentyl glycol were weighed and heated to 140 ° C under nitrogen in one hour. In a further 9 hours was heated to 220 ° C and condensed at this temperature until an acid number less than 3 was reached. The polyesterpolyol thus obtained had a viscosity (determined as the flow time of an 80% strength solution of the polyester in methoxypropyl acetate in the DIN 4 cup at 23 ° C.) of 54 seconds and an OH number of 160 mg KOH / g.

Example 2 Preparation of a polycarbonate diol based on 1,4-butanediol and 1,6-hexanediol

1,223 g of 1,4-butanediol and 535 g of 1,6-hexanediol were placed in a flask and heated to 100 ° C. Finally, about 2 1 / h nitrogen were introduced into the diol and 20 mbar vacuum applied and the mixture as long dehydrated (about 2 hours) until the water content was ≤ 0.1%.

Thereafter, 0.44 g of ytterbium (III) acetylacetonate were added, the diol mixture was heated to 110 ° C. Then 2297 g of dimethyl carbonate were run in about 20 minutes and kept the reaction mixture under reflux for 24 h. Finally, the temperature was raised to 150 ° C and any distillate was removed. This was followed by a further increase to 180 ° C followed by another distillation phase.

The reaction mixture was cooled to 130 ° C and the pressure was lowered to 10 mbar. This was followed by an increase in the oil bath temperature from 130 ° C to 180 ° C within 2 h, the distillation head temperature did not exceed 60 ° C. After reaching 180 ° C, this temperature was maintained for 6 h.

Subsequently, the reaction mixture was cooled to 130 ° C and the pressure was lowered to 10 mbar. This was followed by an increase in the oil bath temperature from 130 ° C to 180 ° C within 2 h, the distillation head temperature did not exceed 60 ° C. After reaching 180 ° C, this temperature was maintained for 6 h. The reaction mixture was cooled to room temperature and the characteristics of the product determined.

A polycarbonate diol having a hydroxyl number of 57.3 mg KOH / g and a viscosity of 115 Pas at 23 ° C. is obtained.

Example 3 Preparation of a polycarbonate diol based on 1,4-butanediol and 1,6-hexanediol

1239 g of 1,4-butanediol and 542 g of 1,6-hexanediol were placed in a flask and heated to 100 ° C in an oil bath. Finally, about 2 l / h of nitrogen were introduced into the diol mixture and 20 mbar Vakkum applied and the mixture as long dehydrated (about 2 hours) until the water content was ≤ 0.1%.

Thereafter, 0.44 g of ytterbium (III) acetylacetonate added, the diol mixture was heated to 110 ° C. Then 2180 g of dimethyl carbonate were allowed to run in about 20 minutes and the reaction mixture was refluxed for 24 h. Finally, the temperature was raised to 150 ° C and any distillate was removed. This was followed by a further increase to 180 ° C followed by another distillation phase.

The reaction mixture was cooled to 130 ° C and the pressure was lowered to 10 mbar. This was followed by an increase in the oil bath temperature from 130 ° C to 180 ° C within 2 h, the distillation head temperature did not exceed 60 ° C. After reaching 180 ° C, this temperature was maintained for 6 h.

Subsequently, the reaction mixture was cooled to 130 ° C and the pressure was lowered to 10 mbar. This was followed by an increase in the oil bath temperature from 130 ° C to 180 ° C within 2 h, the distillation head temperature did not exceed 60 ° C. After reaching 180 ° C, this temperature was maintained for 6 h. Thereafter, the reaction mixture was cooled to room temperature and the characteristics of the product determined.

There is obtained a polycarbonate diol having a hydroxyl number of 113.4 mg KOH / g and a viscosity of 13600 mPas at 23 ° C.

Example 4 (comparison for component I)

Bayhydrol ^® PR 240:

anionically hydrophilicized PUR dispersion based on polyester with a solids content of 40% and an average particle size of 100-300 nm (Bayer AG, Leverkusen, DE)

Example 5 (comparison for component I)

Bayhydrol ^® PR 340:

anionically hydrophilic PUR dispersion based on a polycarbonate diol which only 1,6-hexanediol as a diol-building component, with a solids content of 50% and an average particle size of 100-300 nm (Bayer AG, Leverkusen, DE)

Example 6 Nonfunctional PUR Dispersion (Component I) (Inventive)

64.0 g Desmophen ^® 3600, 196.8 g of Example 2 and 10.9 g of polyether LB 25 were heated to 75 ° C. Subsequently, 48.7 g of hexamethylene diisocyanate was added at 75 ° C within 5 min, heated to 100 ° C and stirred at 100 ° C until the theoretical NCO value was reached. The finished prepolymer was dissolved with 568.1 g of acetone at 50 ° C and then a solution of 1.2 g of hydrazine hydrate, 7.70 g of diaminosulfonate, 2.20 g of 1,2-diaminoethane and 82.3 g of water within 5 min. The stirring time was 30 min. The dispersion was carried out by adding 408.4 g of water. After removal of the solvent by distillation in vacuo, no storage-stable dispersion having a solids content of 40.0% was obtained.

Example 7: Hydroxy-functional PUR dispersion of the prior art (comparison)

Bayhydrol ^® XP 2429: aliphatic hydroxy-functional polyester-polyurethane dispersion of the prior art produced by using a polycarbonate diol, which is based solely on 1,6-hexanediol as the diol component, having a solids content of 55% (Bayer AG, Leverkusen, DE)

Example 8 Hydroxy-functional PUR dispersion (component II)

In a 61 reaction vessel with cooling, heating and stirring device 1170 g of the polyester polyol from Example 1 were initially charged in a nitrogen atmosphere and together with 1140 g of polycarbonate diol from Example 2, 90 g of trimethylolpropane, 120 g of dimethylolpropionic acid and 3.8 g of tin ( II) -octoate heated to 130 ° C and homogenized for 30 min. The mixture was then cooled to 80 ° C, 480 g of hexamethylene diisocyanate added with vigorous stirring, heated to 140 ° C using the exotherm and the mixture kept at this temperature until no more NCO groups could be determined.

Subsequently, the polyurethane thus obtained was cooled to 90 ° -100 ° C, 47 g of dimethylethanolamine (degree of neutralization 60%) was added, homogenized for 15 minutes and dispersed with 2270 g of demineralized water. The resulting aqueous polyurethane resin dispersion had an OH content (100%) of 1.4%, an acid number (100%) of 16.8, an average particle size of 110 nm and a viscosity of about 2020 mPas ( 23 ° C, D = 40 s ^-1 ) at a solids content of 51.2 wt .-%.

Example 9 Hydrozyfunctional PU Dispersion (Component II)

In a 61-reaction vessel with cooling, heating and stirring 1170 g of the polyester polyol from Example 1 were initially charged and together with 1140 g of polycarbonate diol from Example 3, 90 g of trimethylolpropane, 120 g of dimethylolpropionic acid, 125 g of N-methylpyrrolidone and 3 , 8 g of tin (II) octoate heated to 130 ° C and homogenized for 30 min. The mixture was then cooled to 80 ° C, 480 g of hexamethylene diisocyanate added with vigorous stirring, heated to 140 ° C using the exotherm and the mixture kept at this temperature until no more NCO groups could be determined.

Subsequently, the polyurethane thus obtained was cooled to 90 ° -100 ° C, 39 g dimethylethanolamine (degree of neutralization 50%) was added, homogenized for 15 minutes with 2270 g of demineralized water. The aqueous polyurethane resin dispersion thus obtained had an OH content (100%) of 1.4%, an acid number (100%) of 16.3, an average particle size of 150 nm and a viscosity of about 1680 mPas ( 23 ° C, D = 40 s ^-1 ) at a solids content of 55.9 wt .-%.

Application technical part

Examples 1-9 are used for the following performance tests for the production of softfeel coatings:

The parent lacquer is prepared by predispersion by trituration over a laboratory shaker. The temperature of the material to be ground should not exceed 40 ° C. Then OK 412 approx. 10 min. Stir. After crosslinking, the paint system is set to a flow time of approx. 30 s (DIN ISO 2431, 5 mm nozzle) and conventionally sprayed onto Bayblend ^® T 65. The dry film thickness is between 30 and 40 μm. <b><u> Table 1 </ u></b> Application Examples 10-15 (Comparison) example 10 11 12 13 14 15 Component I: Example 4 137.5 127.5 139.8 Example 5 100.0 100.0 Example 6 100.2 Component II: Example 7 100.0 72.7 72.7 Example 8 100.0 73.3 Example 9 100.0 Additives / pigments: Defoamer DNE 0.8 0.5 0.7 0.8 0.5 0.5 Tego ^® Wet KL 245 1.1 0.9 1.1 1.2 0.9 0.9 Byk ^® 348 1.5 1.4 1.4 1.5 1.4 1.4 Aquacer ^® 535 5.6 4.0 5.2 5.7 4.0 4.0 Sillitin ^® Z 86 19.1 13.9 17.9 19.3 13.9 13.9 Talc IT extra 15.2 11.1 14.3 15.5 11.1 11.1 Bayferrox ^® 318 M 50.8 37.0 47.6 51.5 37.0 37.0 OK 412 10.2 7.4 9.5 10.3 7.4 7.4 Component III: Bayhydur 3100 ^®, 75% in MPA 22.7 16.5 22.7 22.7 16.6 16.5 NCO / OH ratio 1.5 Application condition: approx. 23 ° C and 55% rel. Humidity.
Drying condition: 10 min / RT, 30 min / 80 ° C and approx. 16h / 60 ° C aging example 16 17 Component I: Example 6 140.1 100.2 Component II: Example 8 73.3 Example 9 100.0 Additives / pigments: Defoamer DNE 0.8 0.5 Tego ^® Wet KL 245 1.2 0.9 Byk ^® 348 1.5 1.4 Aquacer ^® 535 5.7 4.0 Sillitin ^® Z 86 19.3 13.9 Talc IT extra 15.5 11.1 Bayferrox ^® 318 M 51.5 37.0 OK 412 10.3 7.4 Component III: Bayhydur 3100 ^®, 75% in MPA 22.7 34.6 NCO / OH ratio 1.5 Application condition: approx. 23 ° C and 55% rel. Humidity.
Drying condition: 10 min / RT, 30 min / 80 ° C and approx. 16h / 60 ° C aging 0 value after 72h hydrolysis and 1h regeneration at RT example B hardness ¹ GT ² Softening ³ B hardness ¹ GT ² Softening ³ 10 B 0-1 0-1 6B 0 4-5 11 B 0-1 0-1 3B 0 0-1 12 HB 0 0-1 3B 0 3 13 HB 0-1 0-1 B 1 2 14 HB 2 0 2 B 0 0 15 B 1 2 4B 0 1-2 16 B 0 0 B 0-1 0-1 17 B 1 0 B 0 0-1 ¹ pencil hardness test:
The pencil hardening method is a test for determining the paint film hardness. Pencils of different hardness (6B to 7H) on painted specimens are tested at room temperature as follows: The pencil tip is ground horizontally to give a flat, round surface. At an angle of 45 °, the pencil is then pushed over the paint film to be tested, whereby a force that is as constant as possible should be applied. The value of pencil hardness is determined when the paint surface is damaged for the first time.
² determined according to DIN EN ISO 2409 (O = best value, 5 = worst value)
³ Film softening test (fingernail test):
The film softening is determined by means of the film nail sample. The evaluation of the softening by the fingernail sample is as follows:
not scratchable = 0 (best value) scratch-through to the substrate = 5 (worst value)
All coatings according to Example 10-17 have a comparable hardness and excellent feel. However, the results from Table 3 show that, in contrast to the coatings of the invention (Example 16-17) after 72 h with hydrolysis at 90 ° C and 90% relative humidity, the comparative examples, however, significant film deviations (degradation by hydrolysis (Comparative Table 3 column B Hardness / softening)), whereas the coatings of Examples 16-17 according to the invention show no softening, ie are significantly more stable to hydrolysis.

Claims (12)

Containing aqueous coating compositions I) hydroxyl-free polyurethanes and / or polyurethane ureas, II) ionically modified, hydroxyl and / or amino-containing polyurethanes and / or polyurethane ureas and III) at least one crosslinker, characterized in that the components (I) and (II) contain polycarbonate polyols which have a proportion of at least 25 wt .-% of 1,4-butanediol as a synthesis component. Aqueous coating compositions according to claim 1, characterized in that the polycarbonate polyols have 45 to 100 wt .-% 1,4-butanediol and 0 to 55 wt .-% of 1,6-hexanediol as structural components. Aqueous coating compositions according to claim 1, characterized in that the polycarbonate polyols comprise 60 to 100% by weight of 1,4-butanediol and 0 to 40% by weight of 1,6-hexanediol as structural components. Aqueous coating compositions according to claim 1, characterized in that the polycarbonate polyols have an average hydroxyl functionality of 1.6 to 4. Aqueous coating compositions according to claim 1, characterized in that the polycarbonate polyols contain a mixture of 1,4-butanediol and 1,6-hexanediol as structural components and have an average hydroxyl functionality of 1.9 to 2.05. An aqueous coating composition according to claim 1, characterized in that component (II) is a polyurethane polymer based on a polyester urethane and a polycarbonate polyol. An aqueous coating composition according to claim 1, characterized in that the crosslinker (III) is a polyisocyanate having free isocyanate groups based on aliphatic or cycloaliphatic isocyanates. Two-component paint containing the coating compositions according to claim 1. Use of the coating composition according to claim 1 for coating mineral building material surfaces, metallic surfaces or coatings containing asphalt or bitumen, painting and sealing of wood and wood-based materials or plastic surfaces or as a high-gloss finish. Use of the coating compositions according to claim 1 for the production of soft-feel coatings on plastic or wood substrates. Softftfeel lacquer containing the coating compositions according to claim 1. Multi-layer construction comprising a topmost layer which is a clear or topcoat layer and contains a softfeel lacquer according to claim 11.